There is only ONE simulcast site in your county according to the database.
Spokane Regional Emergency Communications System Trunking System, Spokane, Washington
I checked, and other than the "jail" site, all others are noted as being multicast. Which means depending on where you are at in the county you may not need an SDS type of scanner at all. A Uniden P2 could suffice. The SDS line of scanners are what can help with simulcast distortion.
So with that being said, what town or towns do you plan on monitoring? That will then dictate what scanner you may want to purchase.
Also note that there is a whole lot of encryption already. The DE in the third column means encryption.